hman: Replace Unicode minus with ASCII dash

Now, in the HTML documents generated by the `hman` command, the HTML
Unicode entity for the minus symbol is replaced with a simple ASCII
'-'. This allows us to copy+paste command line options easier (for some
reason, groff was generating Unicode minus signs for strings like
"--patch" and the like.)
brew-wrapper: add new subcommand, 'new'

This command will show all new homebrew formulas since a given date.
Internally, it goes to the homebrew formula directory and each tap,
then uses git to find the first commit since the given date. It then
uses git difftree to output all the files added between that commit and
HEAD, and outputs them in a nice column.